Pottermore does not open to wider use until October, but has already been inundated by Harry Potter fans. There have been more than 22m views of the webpage, peaking at some 50,000 requests per second on 3 August, as readers rushed to become one of the million users chosen to receive early access and a chance to shape the website's development. The site is free to use – Rowling has said that she wanted to "give back to the Harry Potter readership", who number in their hundreds of millions worldwide – but it will be the only sales outlet for ebook versions of the seven Potter titles.

On entering the site, users begin to travel through the world of Harry Potter and the Philosopher's Stone, following in the footsteps of Harry and learning new facts about his world as they open an account at the goblin bank Gringotts, travel up and down Diagon Alley shopping for equipment for school and choosing a wand. Unlocking new content as they progress through the storyline, they can click on and collect items for their "trunk", build and evolve their profiles, adding their own drawings, collecting books and chocolate frog cards, learning spells and brewing potions. A Pottermore account can also be connected to a Facebook account, with users able to make friends – and even take part in wizarding duels once they reach a certain point on the website.

Comments from early users are already positive: "This is amaazing," writes IceDragon, while another user praised the "Beautiful artwork!" "This is very cool. Very unique website. I love the extra content," said CrimsonDream55, but NoxThorn88 "would have expected a little more action".

"I think Pottermore has the potential to be a lasting focal point for the Harry Potter brand – The Leaky Cauldron for the fans. I think the fact that it incorporates new content, a social networking element, and is also the only place people will be able to buy the ebooks will prove to be quite a potent combination ... Having the ebooks there exclusively is a bit of a masterstroke in terms of ensuring people visit the site and engage with it, as is the way they are going to stagger the release of the content," said Charlotte Williams from the Bookseller, an early user of the site. "It'll be interesting to see whether it can act as a first port of call and draw new readers to the books, or whether it'll more be used by existing diehard Potterites."

Rowling has written reams of new material – 18,000 words at the last count, but still growing – for Pottermore, as well as mining her archives to share notes she made when writing the novels. Nuggets unearthed on an early trawl through the site include the news that Rowling unconsciously based the Dursleys' gloomy home on Privet Drive on a childhood home of her own in Winterbourne, near Bristol. "I first became conscious of this when I entered the number four Privet Drive that had been built at Leavesden Studios, and found myself in an exact replica of my old house, down to the position of the cupboard under the stairs and the precise location of each room," the author writes. "As I had never described my old home to the set designer, director or producer, this was yet another of the unsettling experiences that filming the Potter books has brought me."

She also gives humorous background to the long-running animosity between Harry's parents and the Dursleys – "Vernon tried to patronise James, asking what car he drove. James described his racing broom" – and explains why wizards don't need the metric system. "Witches and wizards are not averse to laborious calculations, which they can, after all, do magically, so they do not find it inconvenient to weigh in ounces, pounds and stones; measure in inches, feet and miles; or pay for goods in Knuts, Sickles, and Galleons," she writes.

The site is currently based on the first novel in the series, Harry Potter and the Philosopher's Stone, with further books in the series to be added in the new year.

Williams said that other authors would be watching the site's development with interest. "I think other big-name brands will look very carefully to see what success it has, and if a high level of interest and excitement can be maintained," said Williams. "By retaining the digital rights to her books, and selling the ebooks exclusively through this site, JK Rowling is bypassing not only her publishers but also retailers, so it's a strategy that would only work with the biggest of brands. (And not many authors nowadays still retain the digital rights to their work.) This kind of re-wiring of publishing relationships – agents acting as publishers, publishers acting as agents, authors acting as publishers – is becoming more common, but I'd say this is the most high-profile experiment yet in digital disintermediation."